Evolution of Interstellar Ices

Infrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Ices in molecular clouds are dominated by the very simple molecules H₂O, CH₃OH, NH₃, CO, CO₂, and probably H₂CO and H₂. More complex species including nitriles, ketones, and esters are also present, but at lower concentrations. The evidence for these, as well as the abundant, carbon-rich, interstellar, polycyclic aromatic hydrocarbons (PAHs) is reviewed. Other possible contributors to the interstellar/pre-cometary ice composition include accretion of gas-phase molecules and in situ photochemical processing. By virtue of their low abundance, accretion of simple gas-phase species is shown to be the least important of the processes considered in determining ice composition. On the other hand, photochemical processing does play an important role in driving dust evolution and the composition of minor species. Ultraviolet photolysis of realistic laboratory analogs readily produces H₂, H₂CO, CO₂, CO, CH₄, HCO, and the moderately complex organic molecules: CH₃CH₂OH (ethanol), HC(=O)NH₂ (formamide), CH₃C(=O)NH₂ (acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C₆H₁₂N₄), as well as more complex species including amides, ketones, and polyoxymethylenes (POMs). Inclusion of PAHs in the ices produces many species similar to those found in meteorites including aromatic alcohols, quinones and ethers. Photon assisted PAH-ice deuterium exchange also occurs. All of these species are readily formed and are therefore likely cometary constituents. This revised version was published online in June 2006 with corrections to the Cover Date.     

Rethinking national and global security: The role of space-based observations

In 1955 US President Eisenhower made his Open Skies proposal to the USSR, suggesting an exchange of blueprints showing the location of military installations in the two countries. The proposal was rejected at the time, but today the proliferation of remote sensing technology, along with interrelated security concerns, suggests that the time has come to rethink and update the concept. In this paper the author explains his recent proposal to the US Congress that a national commission be established to explore how information gathered by civilian remote sensing satellites could increase international security and stability without jeopardizing national defence.     

Similarity of the infrared spectrum of an Orgueil organic polymer with interstellar organic compounds in the line of sight towards IRS 7.

We present a comparison between the IR spectrum of the galactic center source IRS 7 and the spectrum of a carbonaceous polymer from the Orgueil meteorite. We have obtained an almost perfect match between the two spectra in the region between 3020-2790 cm-1, which suggests that the chemical composition of the interstellar organic matter and that of the meteorite polymer are similar or that the meteoritic polymer could be a well preserved interstellar organic molecule. Assuming that the meteoritic polymer has the same C/H ratio as these interstellar molecules, we find that 45 % of the total abundance of carbon in the line of sight toward IRS 7 is trapped in such an interstellar organic grain material.     

The solar corona: A testing ground for plasma astrophysics

The extension of solar surface activity models to the domain of stellar activity, and the possibility of testing such extensions, are discussed.     

欧洲通过内外的合作推动无人机的发展

欧洲正在通过欧洲各国之间及其与非欧洲国家之间的合作,加速推动欧洲无人机的发展。在过去的两年间,欧洲为了缩短与美国及以色列在无人机领域的差距,已经作了艰苦努力,开始自主开展无人作战飞机(UCAV)以及中空长航时无人侦察系统的研制工作,并在美国及以色列的经验基础上,重新评估对战术无人机的需求。而海军对垂直起降无人机的需求也逐渐明朗化了。     

The Cluster Spatio-Temporal Analysis of Field Fluctuations (STAFF) Experiment

The Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment is one of five experiments which together comprise the Wave Experiment Consortium (WEC). STAFF consists of a three-axis search coil magnetometer to measure magnetic fluctuations at frequencies up to 4 kHz, and a spectrum analyser to calculate in near-real time aboard the spacecraft, the complete auto- and cross-spectral matrices using the three magnetic and two electric components of the electromagnetic field. The magnetic waveform at frequencies below either 10 Hz or 180 Hz is also transmitted. The sensitivity of the search coil is adapted to the phenomena theo be studied: the values 3 × 10^-3 nT Hz^-1/2 and 3 × 10^-5 nT Hz^-1/2 are achieved respectively at 1 Hz and 100 Hz. The dynamic range of the STAFF instruments is about 96 dB in both waveform and spectral power, so as to allow the study of waves near plasma boundaries. Scientific objectives of the STAFF investigations, particularly those requiring four point measurements, are discussed. Methods by which the wave data will be characterised are described with emphasis on those specific to four-point measurements, including the use of the Field Energy Distribution function.     

碰摩转子的弯曲和扭转振动分析

建立了一个新型多自由度的转子动静碰摩模型。应用该模型 ,重点研究了动、静碰摩引起的转子弯曲和扭转非线性耦合振动。大量的数值计算表明 ,不同碰摩情况下转子具有不同的弯曲和扭转振动响应。转静碰摩激起转子扭转自振频率振动。提出了从转子扭转振动的变化来诊断转静碰摩故障的方法 ,并探讨了此方法的可行性和有效性。     

The Cassini Ultraviolet Imaging Spectrograph Investigation

The Cassini Ultraviolet Imaging Spectrograph (UVIS) is part of the remote sensing payload of the Cassini orbiter spacecraft. UVIS has two spectrographic channels that provide images and spectra covering the ranges from 56 to 118 nm and 110 to 190 nm. A third optical path with a solar blind CsI photocathode is used for high signal-to-noise-ratio stellar occultations by rings and atmospheres. A separate Hydrogen Deuterium Absorption Cell measures the relative abundance of deuterium and hydrogen from their Lyman-α emission. The UVIS science objectives include investigation of the chemistry, aerosols, clouds, and energy balance of the Titan and Saturn atmospheres; neutrals in the Saturn magnetosphere; the deuterium-to-hydrogen (D/H) ratio for Titan and Saturn; icy satellite surface properties; and the structure and evolution of Saturn’s rings.This revised version was published online in July 2005 with a corrected cover date.     

Non-cultural methods of human microflora evaluation for the benefit of crew medical control in confined habitat

Current control of human microflora is a great problem not only for the space medicine but also for practical health care. Due to many reasons its realization by classical bacteriological method is difficult in practical application or cannot be done.To evaluate non-cultural methods of microbial control of crews in a confined habitat we evaluated two different methods.The first method is based on digital treatment of microbial visual images, appearing after gram staining of microbial material from natural sample. This way the rate between gram-positive and gram-negative microbe could be gained as well as differentiation of rods and cocci could be attained, which is necessary for primary evaluation of human microbial cenosis in remote confined habitats.The other non-culture method of human microflora evaluation is gas chromatomass spectrometry (gcms) analysis of swabs gathered from different body sites. Gc-ms testing of swabs allows one to validate quantitative and special microflora based on specific lipid markers analysis.